1. Field of the Invention
The invention relates generally to a gyratory or cone crusher.
2. Background of the Related Art
Gyratory crushers or cone crushers are characterized by crushing or crusher heads having a generally cone-shaped outer surface, which are mounted to undergo gyratory motion. The cone-shaped crusher head of a gyratory crusher is generally centered about a head axis that is angularly offset from a vertical crusher axis generally centered through the crusher. The outer surface of the head is generally protected by a replaceable mantel.
The crushers are further characterized by a bowl-shaped member, sometimes referred to as a concave or bonnet, disposed in an inverted position generally over the cone-shaped crusher head and centered about the vertical crusher axis. The inner surface of the bowl-shaped member is protected by a replaceable bowl liner. The outer dimensions of the head and mantel are smaller than the corresponding inner dimensions of the bowl liner. The head is mounted such that there is a space between the mantel and the bowl liner, sometimes referred to as the "crushing chamber" or "crushing cavity". The volume of the crushing cavity can be increased by altering the shape of the exposed surface of the bowl liner and/or the shape of the exposed surface of the mantel. It can also be increased or decreased by vertically adjusting the elevation of the mantel relative to the elevation of the bowl liner. The bowl-shaped member has an upper opening through which material to be crushed can be fed into the crushing cavity.
The smallest distance between the mantel and the bowl liner at the bottom of the crushing cavity is called the "closed side setting" or "setting" of the crusher. The width of the setting determines the size of crushed materials operably produced by the crusher. The setting can be enlarged to increase the size of the crushed material produced by the crusher, and can be decreased to reduce the size of the crushed material produced by the crusher. The setting can be adjusted by simply raising or lowering the elevation of the bowl liner relative to the elevation of the crusher head, or by raising or lowering the elevation of the crusher head relative to the elevation of the bowl liner. The difference between the width of the closed side setting and the spacing between the mantel and the bowl liner at the bottom of the crushing cavity directly opposite from the closed side setting, sometimes called the "open" side or "open side setting", is called the "throw" or "stroke" of the crusher.
The small angular offset of the head axis relative to the vertical crusher axis is provided by mounting the head on an eccentric element, or other suitable mounting. The head is caused to gyrate relative to the bowl-shaped member by rotating that mounting or eccentric element. As the eccentric element rotates, one side of the head is caused to approach the bowl liner until it attains the closed side setting while the opposite side of the head recedes from the bowl liner until it simultaneously attains the open side setting. The closed side setting and open side setting operably travel around the periphery of the lower end of the crushing cavity as the eccentric element is rotated, each making a complete revolution around the crusher head for each revolution of the eccentric element. The magnitude of the gyration is determined by the angle that the head axis is offset from the crusher axis and by the location of the point at which those two axes most closely approach or intersect.
State-of-the-art gyratory or cone crushers are generally driven by a horizontally disposed countershaft which radially extends into a lower part of a generally cylindrical crusher housing. An inner end of the countershaft is coupled through a pinion and ring gear to the eccentric element to rotatably drive the eccentric element.
A motor (either electric or combustion) is used to drive the crusher. The speed of the motor, the size ratio of the pulleys on the motor and the crusher, and the gearing of the eccentric element determine the speed at which the head gyrates, sometimes referred to as the "gyrational speed". The gyrational speed selected for each crusher depends on the particular application for which the crusher is to be used. Increasing or decreasing the gyrational speed is usually a matter of changing the speed of the motor, changing the relative sizes of the pulleys on the motor and/or the crusher, and/or changing the gear ratios for the eccentric.
The gyratory or gyrating motion of the cone-shaped crusher head performs a material comminution action on material, such as rock, ore, coal and other hard substances, as the material is fed through the bowl opening into the crushing cavity. The material typically moves by gravity through the annular space or crushing cavity between the exposed surface of the stationary bowl liner and the exposed surface of the cone-shaped mantel. As the gyrating head approaches the liner, it crushes the material; as it recedes from the liner, the material falls farther down the crushing cavity to undergo further crushings during subsequent revolutions of the eccentric member. As the separation between the bowl liner and the head gradually decreases from top to bottom, such progressive crushing action repeatedly occurs until the crushed material is discharged from the bottom of the crushing cavity.
The crushing heads of prior art gyratory crushers generally utilize two different mounting mechanisms--spider-type, wherein head mounting support is provided both above and below the crushing head, and spiderless, wherein head mounting support is provided only from below the crushing head. Obviously, greater demands are placed on a spiderless mounting mechanism due to the moments randomly generated during crushing processes.
Further and due to their massiveness, spiderless crushing heads are generally held in place gravitationally on its underlying mounting mechanism. During high speed operations, however, the crushing head tends to levitate or "de-seat", which occurs as the radial acceleration force exceeds the gravitational component of the crushing head weight that normally maintains the crushing head seated on its mounting mechanism. Obviously, the downwardly directed forces generated during actual crushing operations is more than sufficient to prevent the crushing head from levitating; the problem arises primarily during startup or when the crusher has temporarily emptied between inputs of material to be crushed. Unfortunately, levitation of a crushing head that is supported by bearings radially displaced from the longitudinal axis of the crushing head, particularly during high performance crushing operations, substantially increases wear and maintenance over that observed for such crushers that do not experience levitation.
What is needed is a gyratory crusher that has a mechanism for positively preventing the crushing head from levitating from support bearings radially displaced from a longitudinal axis thereof.